Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$152.88	6.868%	$163.3798	$163.38	$163.40	$163.40
Purchase #2	$97.83	7.549%	$105.2152	$105.22	$105.20	$105.20
Purchase #3	$80.52	5.613%	$85.0396	$85.04	$85.05	$85.00
Purchase #4	$103.92	5.152%	$109.274	$109.27	$109.25	$109.30
Purchase #5	$57.89	7.139%	$62.0228	$62.02	$62.00	$62.00
Purchase #6	$164.93	12.329%	$185.2642	$185.26	$185.25	$185.30
Purchase #7	$162.46	13.433%	$184.2833	$184.28	$184.30	$184.30
7 purchase totals =	$820.43		$894.4789	$894.47	$894.45	$894.50